pieces, nearly of the size of the intended coin. The cutting-out press, Fig. 602, is a beautiful contrivance, invented by Boulton, of Soho. It consists of a cast-r, Fig. 602, is jointed to a piece fitted so as to slide iron frame, F, on a stone basement: a screw, s, fitted through the top of the frame, acts on a slider or roller, R, moving up and down in the frame. At the lower end of the slider is a steel punch, p, equal

wooden spring, against which the balance-weight | vent any dumb or unsound pieces being sent to the strikes, to arrest its motion when it has made the other department. required stroke to punch the plate.

press is cylindrical at the upper and lower ends, where it is seen at DD, and these ends are accurately fitted in collars bound tight by screws, a a; the real screw or worm part is concealed within the solid metal B: its object is to force the die down, the lateral guidance being effected by the collars a. Arrangements are also made for removing every piece of money which is struck, and for feeding the press with a fresh blank piece. HIK is a lever, of which I is the fulcrum: it is supported on a bar, q fixed vertically from the cheek of the press, and steadied by a brace h. The upper end of the lever is actuated by a sector, 7, fixed upon the screw, D. When the screw turns round, a groove in the sector, being of a spiral curve, moves the end H of the lever to and from the screw; and the lower end, K, of the lever, being longer, moves a considerable distance to and from the centre of the press. b is a socket or groove in a piece of metal fixed to the perpendicular bar, q, in which the upper end of the lever is guided. The lever K moves a slider, L, which is supported in a socket o, and this slider is directed exactly to the centre of the press, and on the level of the upper surface of the die. The slider is a thin steel plate, made in two pieces united by a joint: the extreme end is made with a circular cavity, so that a hen the two limbs shut together, they will grasp a piece of money between them, and hold it by the edge; and on separating the limbs, the piece will drop out. On the top of the socket, to the left of 5, is a tube which an attendant keeps filled with blank pieces: this tube is open at the bottom to the slider, and the pieces rest upon it. When the screw of the press is screwed down, the slider draws back to its furthest extent, and the circle formed at the end between its limbs comes exactly beneath the tube. The limbs being open, a blank piece of coin drops down into the circle of the slider; then the screw of the press, in returning, moves the lever HIK and the piece L: this closes the circle upon the blank piece. The slider is pushed forward in its socket, and the piece is carried forward upon the die, and in the act of doing this the slider pushes off the piece last struck. The screw having now arrived at its highest position, begins to descend, and the slider L to return; but just at this point the limbs open, and leave the blank piece upon the die. As the screw of the press descends, the ring before noticed rises up to enclose the piece while it receives the stroke, and the slider P at the same time returns to take another blank from the tube.

ceiling, and is worked by steam-driven machinery | keep it firmly in its cell. The great screw of the situated in the room above. The loaded arms, RR, strike against blocks of wood, whereby they are prevented from moving further than is necessary: if it were not for this precaution, the hard steel dies might come in contact, and be broken. The piece of blank coin is contained within a steel ring or collar while it is being stamped, and this not only preserves its circular figure, but also effects the milling at the edge. This collar rests upon a three-pronged spring, which bears it upwards, and the opening through it fits upon the neck of the lower die, the upper surface of the collar and of the die being in one plane; but the collar admits of being raised up upon the neck, so as to form a recess or cell adapted to receive a piece of money. The collar is thus made to rise and fall by means of the levers, G, which are fitted upon centrepins, or joints, in a large ring placed on the outside of the box which contains the lower die, and is fixed firmly upon it, as at 5 and 6. These levers, &, are forked at the outer ends, to admit studs at the lower ends of iron rods, EE, which rise up through holes in the solid metal of the press, and are united to a collar, G, fitted on the upper part of the screw, D. When the screw of the press is turned back, and the upper die is raised up, the rods raise the outside ends of the short levers, G, and the inside ends depress the collar: a blank piece of money is then placed, by means of steel fingers, upon the die, and when the screw is turned, to bring down the upper die upon it, to stamp the impression, the levers G are released, and the three-pronged spring lifts up the collar, so as to surround the piece of money while the blow is being struck. The press then immediately returns by its recoil, and the levers, G, force the collar down upon the neck of the die, and leave the piece free. The lower die is fixed in a box, 6, by four screws, which allow it to be precisely adjusted beneath the upper die. The upper die is also firmly attached by four screws in a box, which is fitted in a ring or collar, F, the arms of which are attached to the rods EE by nuts at each end; and this makes the collar F and the box 3 always follow the screw, and keep a close contact with the end of the screw, which enters into a cell in the top of the box 3, but leaves the screw at liberty to turn round independently of the box. 2 is a ring, fastened by its screws to the screw of the press descending from this ring is a claw, which enters the cavity in the edge of the box 3: this cavity is nearly three times as wide as the claw, so that the screw can turn round a certain distance without turning the box 3; but beyond the limits of this motion, the screw and the die will turn round together. The object of this arrangement is to press the upper die down upon the coin with a twisting motion; but if the die were to rise up with a similar motion, it would abrade and destroy the fine impression hence, the notch in the ring 3 is so wide as to allow the screw to return and raise the die from immediate contact with the coin before it begins to turn round with the same motion as the screw. 4 is a box, screwed over the box for the upper die in order to

The coining-room at the Mint contains eight presses: they are placed in a row on a stone basement, on which very strong oak pillars are erected, reaching to the ceiling. Each press is contained between four such pillars, and iron braces are fixed horizontally from one pillar to another.

The money thus coined is passed through tubes of the diameter of the different species, whereby any defect in size is detected. It is then weighed up in journey-weights for delivery to the importers of the

COLOCYNTH-COLUMBIUM-COMB.

419

bullion, the gold in 15 lbs., the silver in 60lbs., Troy. | coarsest to those which have from 40 to 45 teeth in But before delivery to the importers, the money is the inch. The blades or plates of the saw are made of inspected as to its workmanship, and pixed. The thick steel, and are ground away on the edge, as at a process of pixing consists in taking from every journey- or b, as thin as the notches in the comb, and they have weight a pound, promiscuously, and weighing in an from 10 to 20 points in the inch of slight pitch. [Sce accurate balance: if the weight be not satisfactory, SAW.] The plates are fixed in two grooves of the the coin is ordered to be melted up and recoined at stock by means of the stuffing, which consists of two the expense of the moneyers.' long wooden wedges, or folds of brown paper; contact COIR. See COCOA-NUT. between the plates is prevented by a thin slip of COKE. See CARBON. metal, called a languid, l, which is of the thickness of COLLIERY. See COAL. the teeth required in the comb c. One blade is in advance of the other from to of an inch; at the first process a notch nearly of the full depth is made in the comb, and a second notch is commenced; at the next process the notch in advance is deepened, and a third commenced, and so on consecutively. By this means the teeth can be cut in a regular manner, for the very action of cutting out one tooth scores out a place for the saw for the next adjacent tooth. The openings thus formed are afterwards thinned out and finished by means of thin wedge-shaped files, called floats. Some of these files are shown in section in Fig. 606,

COLOCYNTH, a valuable medicinal agent derived from the bitter cucumber, (Cucumis colocynthis,) growing in Turkey, India, &c. The drug consists of the dried pulp, which is white, spongy, and of a nauseous and bitter taste, but without smell. When adulterated, or badly dried, it is of a dirty brown or deep grey colour. This medicine, which is a powerful drastic cathartic, is too violent to be administered alone, but it is given in union with other medicines. Camphor mitigates its violence.

COLOUR. See LIGHT.

COLUMBIUM, a rare metal, found in the Swedish minerals tantalite and yttro-tantalite, and hence sometimes called TANTALUM. (Ta .185.)

COMB. The materials employed in the manufacture of combs are wood, horn, tortoiseshell, ivory, bone, and metal. The preparatory processes for the two principal materials will be described under HORN and TORTOISESHELL. The materials are first prepared in the form of plates, and the methods of cutting the teeth in these have led to some ingenious contrivances. The old method of doing this is by means

Fig. 605.

a

of a double saw, called a stadda, Fig. 605; it has two blades, so contrived as to give with ease and exactness the intervals between the teeth of combs, from the

(1) The reader interested in this subject is referred to the Rev. Rogers Ruding's "Annals of the Coinage of Great Britain and its Dependencies," Third Edition, enlarged, &c. 3 vols. 4to. London. 1840. A great variety of details respecting the Royal Mint, as well as the mints of other countries, will be found in the "Report from the Select Committee of the House of Commons on the Royal Mint," ordered to be printed 30th June, 1837. The mechanical details of the Royal Mint are well described and illus

trated by four quarto plates of figures in the Article COINAGE in the "Encyclopædia Britannica," vol. vii., which has assisted us

in the preparation of this Article. We have also to express our

obligations to Professor Brande, of the Royal Mint, for permission to inspect the processes, and for explanatory details.

Fig. 606.

the teeth being shown at the points indicated by the double lines; a is a float, b the graille, c the found, d the carlet, e the topper; these names are corruptions from the French, and indeed the art of combcutting is almost entirely derived from the French. f represents what is called a quannet, a sort of rasp, with coarse-filed teeth; this is the ordinary flat file of the comb-makers, and in using it the work is mostly placed on the knee as a support.

The

The introduction of the circular saw led to some improvement in comb-cutting, especially with boxwood or ivory as the material. In a machine invented by Messrs. Pow and Lyne the plate is fixed in a clamp suspended on two pivots parallel with the spindle of the circular saw. By the revolution of the handle, a cam first depresses the ivory on the revolving saw, cuts one notch, and quickly raises it again; the handle in completing its circuit shifts the slide that carries the suspended clamp to the right, by means of a screw and ratchet movement. teeth are cut with great exactness, and as quickly as the handle can be turned; they vary from about 30 to 80 teeth in the inch, and such is the delicacy of some of the saws that even 100 teeth may be cut in an inch of ivory: the saw runs through a cleft in a small piece of ivory, fixed vertically and radially to the saw, to act as the ordinary stops, and prevent it from being bent or displaced sideways. Two combs are usually placed one over the other and cut at once; occasionally the machine has two saws, and cuts four

combs at once.

EE 2

In making small side-combs of tortoiseshell the | to the toothed-wheel w. From the centre of this material is economised by the process of parting, as it wheel projects a solid screw which turns in the hollow is called. This method is said to be the invention of one, and consequently moves the bed in one direction an artisan named Ricketts, who was led to it by being or the other, according as the toothed wheel is turned engaged in the production of ornamented tortoise- one way or the other. The wheel w receives its moshell combs, [see HORN and TORTOISES HELL,] in which tion from the wheel w', which being placed on the the decorated parts were formed by the pressure of axle a, is turned together with it by the winch . cutters. A machine for making parted combs was But the wheel w' has teeth only on part of its circumdescribed by Mr. Rogers in the 49th vol. of the ference, and therefore, while this is in continued Transactions of the Society of Arts. It has since motion, will give an alternation of motion and rest to been remodelled and improved by Mr. Kelly. The fol- the wheel w, and consequently to the piece of tortoiselowing is from Mr. Rogers's description:-pp, Fig. 607, shell. While this latter is at rest the cutter makes is a plate supporting the other parts, and is secured its stroke, and while the cutter is rising to make anby screws to any suitable bench; h is a winch or other stroke, the piece of tortoiseshell moves through handle attached to the axle a; uu are upright pieces, a space equal to the interval between one tooth of the in which the two ends of the axle work, and u' is an- comb and the next. When these actions have been other upright, between which and u the crank of the repeated along the whole length of the tortoiseshell, axle is situated. From the bottom plate p is a curved Fig. 608 is produced, which is the full size or nearly projecting piece, on which is hinged the bar b; at the end of this bar is a collar c, secured by a screw, and conneeted by means of a link with the cranked part of the axle. When the axle is turned round by means of its winch an alternate up and down motion is given to the bar b; is a loop in which the bar works, and which prevents it from swerving to either side; kis the cutter, and a piece of tortoiseshell, out of which two parted combs are to be made. The cutters

Fig. 607.

Nos. 2 and 3 consist of two sharp blades of steel bent outwards a little at one end, between which are placed wedge-shaped pieces, so as to cause the blades to diverge from each other at the bent end by any required distance; at the other end the blades come nearly but not quite in contact, and this space is filled up by the insertion of the piece No. 4, the sharp tooth of which is so adjusted as to be even with the edge of the blades. When, therefore, this compound cutter is pressed down on the surface of the tortoiseshell, a tooth, such as is shown in No. 5, will be formed. But in order to make a succession of such teeth it is necessary that the piece of tortoiseshell shall have a progressive motion, and that this motion shall be suspended while the cutter is making its blow. These two conditions are effected thus:-in front of the bed on which the tortoiseshell t is laid is a rectangular opening, into which a heated bar is put, which, by keeping the tortoiseshell warm, prevents it from splitting by the action of the cutter. The bed slides in a dovetail groove made in the plate p, and has a hollow screw in that end of it which is adjacent

Fig. 608.

so, and a slight pull will part the two pieces, each of which is a separate comb. Such combs are called parted, the saw not being used on them, and they are often made of fine stained horn instead of tortoiseshell.

COMBUSTION, a chemical process, in which two substances at least enter into combination, and heat and a new compound are the results. Thus, when antimony in powder, or copper in the form of thin leaf, is presented to chlorine, a combination is instantly effected between these bodies, and a chloride of antimony or of copper is the result, attended at the moment of combination with heat and light. It is usual to reckon five supporters of combustion, viz. oxygen, chlorine, iodine, bromine, and fluorine. Of these, the first is by far the most important. It is one of the constituents of the atmosphere and of water; it enters abundantly into the composition of most bodies in their natural state, and is altogether so important that without it no animal could live, no plant could grow, and, generally speaking, no flame could burn; the other four supporters of combustion, as they are termed, would not support animal or vegetable life.

Before the discovery of oxygen gas combustion was explained by supposing that all combustible bodies contained a certain principle called phlogiston, the presence of which enabled bodies to burn. It was further supposed that when a body burned, phlogiston was liberated, and that when a body had lost phlogiston it ceased to be combustible; it was then said to be dephlogisticated. The heat and light which accompany combustion were attributed to the rapidity with which phlogiston was evolved.

But according to this hypothesis, a combustible body having undergone the process of combustion